Do you know what she was updating it to? That's the most important thing. Either way, two possible solutions.
The first, and quickest, requires you to have another Mac about. Boot her MacBook in target firewire mode (turn it on while holding the 'T' key until the firewire logo appears on the MacBook's screen) and then connect a firewire cable from there to your Mac. Then grab either the 10.4.11 or 10.5.2 combo updates and install them to her machine.
The second slower but probably more foolproof method is to grab the original OS discs that came with the MacBook and perform and 'archive and install', but MAKE SURE you tick the 'preserve users and network settings' checkbox. Once you've done that, you can just update everything from there.